Well....not quite. I've set up coilovers and struts with helpers, tenders, dual springs and even triple springs. It all depends on the application.
Here's a set of struts that went on a Subaru STi competing at the Pikes Peak Hillclimb. I used dual spring sets to get the car low, with about three inches of compression travel and 7-10 inches of real droop travel. This setup was done on paper, but we brought a dozen other spring sets with us and dialed it in during on-site testing.
Suspension packages that come out of Europe often have near-zero rate helper springs or low-rate tender springs to keep the spring seated on the perch at full droop to be TUV certified. Our a la carte suspensions are setup for reasonable street and track use and we often use the shortest reasonable spring to gain as much inboard tire clearance as we can. In come applications travel, or ride height is more important than inboard tire clearance and we accommodate it.
On the subject of what rate is the spring you got, you can take a few measurements and get a rough calculation of the spring rate. First Google hit has an online calculator:
http://www.pontiacracing.net/js_coil_spring_rate.htm